1. Field of the Invention
The present invention relates to a colorant-containing curable composition for a color filter that is suitable for forming a colored image of a color filter for use with a liquid crystal display device, a solid image pickup element (such as a CCD or a CMOS) and the like, a color filter, and a method for manufacturing the same.
2. Description of the Related Art
As methods for manufacturing a color filter for use with a liquid crystal display device or a solid image pickup element, dyeing methods, printing methods, electrodeposition methods, and pigment dispersion methods are known.
Among these, the pigment dispersion method is a method for manufacturing a color filter by a photolithography method including using a colored radiation-sensitive composition in which pigments are dispersed in various photosensitive compositions. The pigment dispersion method has an advantage of stability against light, heat and the like, because of the use of pigments. In addition, because the pigment dispersion method conducts patterning by the photolithography method, it gives high positioning accuracy. Therefore, the pigment dispersion method has been widely used as a method which is suitable for manufacturing color filters for color displays of large-screens and high-precision.
In order to manufacture a color filter by the pigment dispersion method: a radiation-sensitive composition is coated on a glass substrate by means of a spin coater, a roll coater, or the like, and dried to form a coating film; the coating film is exposed to light through a mask pattern, and developed to form colored pixels; and this cycle of operation is repeated for each color.
A negative photosensitive composition, which uses a photopolymerizable monomer and a photopolymerization initiator in an alkali soluble resin, is conventionally known as a specific example of the sensitive compositions used in the pigment dispersion method (see, for example, Japanese Patent Application Laid-Open (JP-A) Nos. 2-199403, 4-76062, 5-273411, 6-184482, and 7-140654).
In recent years, for applications such as solid image pickup elements, higher precision of the color filter has been demanded. However, it is difficult to further improve the resolution with the conventional pigment dispersion system. In addition, there are problems, such as irregular color being caused by coarse particles of the pigment. Therefore, the above-mentioned pigment dispersion method has not been suited for applications such as solid image pickup elements where extremely fine patterns are required.
In order to solve the above-mentioned problems, examples where a solvent or water soluble dye is used have been conventionally known (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2002-278056).
However, the dye-containing curable composition has the following problems (1) to (4).
(1) Generally, coloring matter has a low solubility in either alkali water solutions or organic solvents, thus it is difficult to obtain a liquid curing composition having the desired spectrum.
(2) Dyes often interact with other components in the curable composition, thus it is difficult to adjust the solubility of the curing part and the non-curing part (developability).
(3) When the dye has a low molar absorption coefficient (ε), the dye must be added in a large quantity, thus it is inevitable that the amounts of the other components in the curable composition, such as the polymerizable compound (monomer), the binder, and the photopolymerization initiator, must be reduced. This presents such problems as the lowering of the curability of the composition, the heat resistance after curing, and the developability of the (non-)curing part.
(4) Dyes are generally inferior in light resistance and heat resistance, as compared to pigments.
In addition, especially for the application for manufacturing of a color filter for a solid image pickup element, it is required that the film thickness be 1.5 μm or less, unlike in semiconductor manufacturing applications. Therefore, the coloring matter must be added to the curable composition in a large quantity, which presents the same problems as mentioned above.
Because of the above-mentioned problems, it has been difficult in practice to meet the requirements for performance for use in extremely fine, thin-film colored patterns for high-precision color filters. Therefore, development of a dye and curable composition which can eliminate the above-mentioned problems has been desired.